3,4-Dichlorobenzaldehyde → 5-[(3,4-Dichlorophenyl)methylidene]-2-sulfanylidene-1,3-thiazolidin-4-one

A 50 mL flask was charged with 899 mg rhodanine (6.75 mmol, 1.0 equiv), 1.77 g 3,4-dichlorobenzaldehyde (10.1 mmol, 1.5 equiv), 1.66 g sodium acetate (20.25 mmol, 3.0 equiv) and 20 mL methanol. The mixture was heated to 65° C. with stirring for 1.75 h. The yellow solid was then filtered and washed (4×MeOH) to give the product 5-(3,4-dichlorophenylmethylene)-4-oxo-2-thionothiazolidine as a yellow solid (1.059 g 3.67 mmol, 54%).